fix(telegram): notify users when agent returns empty response

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/telegram/bot-message-dispatch.ts

@@ -199,6 +199,7 @@ export const dispatchTelegramMessage = async ({
           chunkMode,
           onVoiceRecording: sendRecordVoice,
           linkPreview: telegramCfg.linkPreview,
+          notifyEmptyResponse: info.kind === "final",
         });
       },
       onError: (err, info) => {

src/telegram/bot-native-commands.ts

@@ -484,7 +484,7 @@ export const registerTelegramNativeCommands = ({
             cfg,
             dispatcherOptions: {
               responsePrefix: resolveEffectiveMessagesConfig(cfg, route.agentId).responsePrefix,
-              deliver: async (payload) => {
+              deliver: async (payload, info) => {
                 await deliverReplies({
                   replies: [payload],
                   chatId: String(chatId),
@@ -497,6 +497,7 @@ export const registerTelegramNativeCommands = ({
                   tableMode,
                   chunkMode,
                   linkPreview: telegramCfg.linkPreview,
+                  notifyEmptyResponse: info.kind === "final",
                 });
               },
               onError: (err, info) => {

src/telegram/bot/delivery.ts

@@ -42,12 +42,15 @@ export async function deliverReplies(params: {
   onVoiceRecording?: () => Promise<void> | void;
   /** Controls whether link previews are shown. Default: true (previews enabled). */
   linkPreview?: boolean;
-}) {
+  /** If true, send a fallback message when all replies are empty. Default: false */
+  notifyEmptyResponse?: boolean;
+}): Promise<{ delivered: boolean }> {
   const { replies, chatId, runtime, bot, replyToMode, textLimit, messageThreadId, linkPreview } =
     params;
   const chunkMode = params.chunkMode ?? "length";
   const threadParams = buildTelegramThreadParams(messageThreadId);
   let hasReplied = false;
+  let skippedEmpty = 0;
   const chunkText = (markdown: string) => {
     const markdownChunks =
       chunkMode === "newline"
@@ -75,6 +78,7 @@ export async function deliverReplies(params: {
         continue;
       }
       runtime.error?.(danger("reply missing text/media"));
+      skippedEmpty++;
       continue;
     }
     const replyToId = replyToMode === "off" ? undefined : resolveTelegramReplyId(reply.replyToId);
@@ -255,6 +259,17 @@ export async function deliverReplies(params: {
       }
     }
   }
+
+  // If all replies were empty and notifyEmptyResponse is enabled, send a fallback message
+  if (!hasReplied && skippedEmpty > 0 && params.notifyEmptyResponse) {
+    const fallbackText = "No response generated. Please try again.";
+    await sendTelegramText(bot, chatId, fallbackText, runtime, {
+      messageThreadId,
+    });
+    hasReplied = true;
+  }
+
+  return { delivered: hasReplied };
 }
 
 export async function resolveMedia(